1. Department of Applied Chemistry, National Chiao-Tung University, 1001 Ta-Hsueh Road, Hsinchu 300-10, Taiwan
2. Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
3. Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan first Road, Kaohsiung 807-08, Taiwan